Canis ISSN: 2398-2942

Spinal cord: concussion

Synonym(s): Spinal cord trauma, spinal cord contusion

Contributor(s): Rodney Bagley, Laurent Garosi

Introduction

  • Spinal trauma is a common cause of spinal cord dysfunction in dogs and cats.
  • Spinal trauma can occur either from exogenous or endogenous spinal injury.
  • Cause: exogenous trauma, type I or type II intervertebral disk herniation, acute non-compressive nucleus pulposus disk extrusion.
  • Signs: depend on severity of inciting trauma.
  • Autodestructive mediators come into play within minutes of trauma and persist for several days.
  • Treatment: high dose methylprednisolone succinate.
  • Prognosis: guarded - other life-threatening injuries may be present if exogenous trauma involved.

Pathogenesis

Etiology

  • Automobile trauma.
  • Fall.
  • Trauma from falling object.
  • Projectile missile damage, eg gunshot.
  • Depending upon the position of the animal, the type of force, area of impact and the inherent strengths and weaknesses of the vertebral column, exogenous spinal injury may result in spinal cord concussion.
  • Endogenous trauma: disk herniation or acute non-compressive nucleus pulposus extrusion Spinal cord: acute non-compressive nucleus pulposus extrusion.

Specific

  • Chondrodystrophic breeds predisposed to type I disk disease.
  • Large breeds with a higher incidence of fibrocartilagenous embolism.

Pathophysiology

  • Because the spinal cord is encircled by a rigid, inelastic bony encasement (vertebrae), and because of relatively soft texture of spinal parenchyma, any change in canal diameter results in spinal cord injury.
  • Mechanical injury to nervous tissue (especially axons), results in physiologic or morphologic disruption of nervous impulses.
  • Ultimately, numerous pathophysiological consequences may evolve including ischemia, hemorrhage, alterations in spinal cord blood flow and edema.
  • These secondary events lead to a self-perpetuating process of damage to the spinal cord that often is equally, if not more, detrimental to the spinal cord than the initial mechanical injury (second injury theory).
  • Detrimental events are initiated by the mechanical insult, which causes the release of neurotransmitters, damage to glial and neuronal membranes and damage to the local vasculature → energy failure and increased cell membrane permeability → cascade of events including destruction of the microvascular bed → reduction in perfusion of the injured area → increase in intracellular calcium concentration → free radical production → expanding zone of cellular necrosis and apoptosis.
  • Inciting agent → inflammatory reaction in cord (swelling, hemorrhage, edema) → autodestructive process in nerve tissue that exacerbates initial damage → increased intracord pressure → transmitted centripetally into the grey matter → high metabolic requirement of injured tissue may not be met.
  • Severe cases will also have necrosis of surrounding white matter.
  • May also get primary demyelination of white matter → impaired impulse conduction but with axonal preservation.
  • Mediators: free radicals, free fatty acids, arachidonic acid metabolites, endogenous opioids and monoamines.
  • Other metabolic changes: loss of calcium from and accumulation of potassium in the extracellular space, loss of high energy phosphates, lactic acidosis, reduced intracellular pH.
  • Severe cord contusion may → ascending syndrome Diffuse progressive myelomalacia.

Timecourse

  • Acute onset.
  • Majority of secondary damage occurs within 24 hours of injury and, although cellular apoptosis continues for weeks to months, it is not common for clinical signs of deterioration to be evident much beyond 72 hours following injury.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Olby N (2010) The pathogenesis and treatment of acute spinal cord injuries in dogs. Vet Clin Small Anim 40 (5), 791-807 PubMed.
  • Bruce C W, Brisson B A, Gyselinck K (2008) Spinal fracture and luxation in dogs and cats: a retrospective evaluation of 95 cases. Vet Comp Orthop Traumatol 21 (3), 280-284 PubMed.
  • Olby N J, Harris T, Muñana K, Skeen T & Sharp N J H (2003) Long term functional outcome of dogs with severe thoracolumbar spinal cord injuries: 87 cases (1996-2001). JAVMA 222 (6), 762-769 PubMed.
  • Bagley R S (2000) Spinal fracture or luxation. Vet Clin Small Anim 30 (1), 133-153 PubMed.
  • Bagley R S et al (1999) Exogenous Spinal Trauma - clinical assessment and initial management. Comp Contin Educ Pract Vet 21 (12), 1138-1144 VetMedResource.
  • Meintjes E, Hosgood G & Daniloff J (1996) Pharmaceutic treatment of acute spinal cord trauma. Comp Contin Ed 18 (6), 625-35 VetMedResource.
  • Coates J R, Sorjonen D C, Simpson S T, Cox N R et al (1995) Clinicopathologic effects of a 21-aminosteroid compound (U74389G) and high-dose methylprednisolone on spinal cord function after simulated spinal cord trauma. Vet Surg 24 (2), 128-39 PubMed.
  • Coughlan A R (1993) Secondary injury mechanisms in acute spinal trauma. JSAP 34 (3), 117-22 VetMedResource.
  • Shores A (1992) Spinal trauma. Pathophysiology and management of traumatic spinal injuries. Vet Clin North Am Small Anim Pract 22 (4), 859-888 PubMed.
  • Janssens L A A (1991) Mechanical and pathophysiological aspects of acute spinal cord trauma. JSAP 32 (11), 572-8 VetMedResource.
  • Selcer R R, Bubb W J & Walker T L (1991) Management of vertebral column fractures in dogs and cats - 211 cases (1977-1985). JAVMA 198 (11), 1965-8 PubMed.
  • Bracken M B et al (1990) A randomized trial of methylprednsiolone or naloxone in the treatment of acute spinal cord injury. New England J Med 322 (20), 1405-1411 PubMed.
  • Braund K G, Shores A & Brawner W R (1990) The etiology, pathology and pathophysiology of acute spinal trauma. Vet Med 85 (7), 684-91 VetMedResource.
  • Brawner W R Jr, Braund K G & Shores A (1990) Radiographic evaluation of dogs and cats with acute spinal cord trauma. Vet Med 85 (7), 703-23 VetMedResource.
  • Carberry C A, Flanders J A, Dietz A E et al (1989) Non-surgical management of thoracic and lumbar spinal fractures and fracture/luxations in the dog and cat - a review of 17 cases. JAAHA 25, 43 AGRIS FAO.
  • Smith G K & Walter M C (1988) Spinal decompressive procedures and dorsal compartment injuries - Comparative biomechanical study in canine cadavers. Am J Vet Res 49 (2), 266-73 PubMed.
  • Turner W D (1987) Fractures and fracture-luxations of the lumbar spine - A retrospective study in the dog. JAAHA 23 (4), 459-64 VetMedResource.
  • Berg R J & Rucker N C (1985) Pathophysiology and medical management of acute spinal cord injury. Comp Cont Educ 7 (8), 646-52 VetMedResource.
  • Braughler J M & Hall E D (1983) Lactate and pyruvate metabolism in injured cat spinal cord before and after a single large intravenous dose of methylprednisolone. J Neurosurg 59 (2), 256-61 PubMed.
  • Braughler J M & Hall E D (1983) Uptake and elimination of methylprednisolone from contused cat spinal cord following intravenous injection of the sodium succinate ester. J Neurosurg 58 (4), 538-42 PubMed.
  • Hoerlein B F, Redding R W, Hoff E J & McGuire J A (1983) Evaluation of dexamethasone, DMSO, mannitol and solcoseryl in acute spinal cord trauma. JAAHA 19 (2), 216-26 VetMedResource.
  • Matthiesen D T (1983) Thoracolumbar spinal fracture/luxations - Surgical management. Comp Contin Ed Pract Vet 5 (10), 867-78 VetMedResource.
  • Means E D, Anderson D K, Waters T R & Kalaf L (1981) Effect of methylprednisolone in compression trauma to the feline spinal cord. J Neurosurg 55 (2), 200-8 PubMed.
  • Feeney D A & Oliver J E (1980) Blunt spinal trauma in the dog and cat - Insight into radiographic lesions. JAAHA 16 (6), 885-90 VetMedResource.
  • Stone E A, Betts C W & Chambers J N (1979) Cervical fractures in the dog - A literature and case review. JAAHA 14 (4), 463-71 VetMedResource.
  • Hoerlein B F & Spano J S (1975) Non-neurological complications following decompressive spinal cord surgery. Arch Am Coll Vet Surg 4 (2), 11 Wiley Online Library.
  • Slocum B & Rudy R L (1975) Fractures of the seventh lumbar vertebra in the dog. JAAHA 11 (2), 167-74 VetMedResource.

Other sources of information

  • Bruecker K A & Seim III H B (1993)Spinal fractures and luxations.In:Texbook of Small Animal Surgery2nd Ed, D Slatter (Ed). Philadelphia: W B Saunders Co. pp 1110-1121.


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